Make CriteriaQuery implement Serializable

While it would be desirable to have CriteriaQuery implement Serializable, it would then imply that MetaModel is also Serializable (and this would imply that org.datanucleus.metadata is Serializable). If the user is deserialising it into a different EMF the metamodel could potentially be different, so there are issues around allowing this

Description

While it would be desirable to have CriteriaQuery implement Serializable, it would then imply that MetaModel is also Serializable (and this would imply that org.datanucleus.metadata is Serializable). If the user is deserialising it into a different EMF the metamodel could potentially be different, so there are issues around allowing this